The designer's toolkit has a variety of simulation tools ranging from 2.5D planar Signal Integrity/Power Integrity tools to 3D Field Electromagnetic Simulation tools.These tools can be utilized for post-layout analysis on Allegro PCB Designer and OrCAD PCB Designerincluding validating insertion loss budgets, timing specifications, propagation delays, impedance mismatches, crosstalk analysis and analyzing power distribution networks.The 2-dimensional transient simulation engine within PSpice can also be utilized to model pcb vias and trace transitions with lossy, distributed, lumped and ideal transmission line PSpice models. Stack up specifications: Backdrilling The image showcases the ability to specify the length of backdrilling within Allegro PCB Designer 3D View within Allegro PCB Designer is shown The image showcases via and layer transitions with differential routing PSpice Advanced Analysis Modeling backdrilling and sequential laminations with PSpice Advanced Analysis The reflection caused by the via stub for through-hole vias can be modeled within PSpice with a certain level of accuracy hence signal integrity decisions on the stack up can be made in terms of the length of the via stub. A simple RLC circuit can be utilized to emulate the via capacitance and inductance. Based on this analysis with a 2D simulation tool design decisions on the stack up can be made including the thickness parameter, type of laminations including sequential laminations and type of drilling including blind, buried vias, back drilled or through-hole vias. A similar analysis can be executed with respect to trace impedance with the Monte Carlo Simulation feature within PSpice Advanced Analysis. The manufacturing files include the drill chart and legend, this provides details on the length of the via and via pad stack. This information can be utilized in terms of input information to model your through-hole vias. Utilize the Monte Carlo feature within PSpice Advanced Analysis to determine the manufacturing yield of the stack up based on specified tolerances. Drill Chart after utilizing PSpice Advanced Analysis Initial decision might have been to utilize backdrilling to remove via stubs however post simulation analysis the design decision is to now utilize sequential laminations. For more information refer to PSpice.com![]()
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